Pensions and Other Benefits (Details) - Net asset value (NAV) [Member] $ in Thousands	Mar. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	$ 101,998
Fixed income
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	34,620
Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	8,945
Cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	$ 0

Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant